Manipulator arm-to-patient collision avoidance using a null-space

A system comprising:

• a base;
• a manipulator arm comprising a proximal portion coupled to the base, a movable distal portion, and a plurality of joints that kinematically couple a plurality of links between the base and the distal portion, the plurality of links together having sufficient degrees of freedom to allow a range of different link states of the plurality of links for a given pose of the distal portion of the manipulator arm;
• an input device;
• and
• a processor-based controller coupled to the manipulator arm and to the input device, the controller being configured to perform operations including:
• receiving a manipulation command from the input device to move the distal portion of the manipulator arm with a first movement at a surgical work site of a patient;
• calculating a displacing movement of the plurality of joints of the manipulator arm in response to the manipulation command so as to implement the first movement, wherein calculating the displacing movement comprises calculating link movement within a null-perpendicular space of a Jacobian, the null-perpendicular space being orthogonal to a null-space of the Jacobian;
• calculating an avoidance movement of the plurality of links of the manipulator arm within the null-space of the Jacobian so as to implement a clearance between the manipulator arm and an outer surface of the patient within a range of motion of the manipulator arm;
• and
• driving the plurality of joints that kinematically couple the plurality of links of the manipulator arm according to the displacing movement and the avoidance movement.